Air-cooled condenser

Abstract

PCT No. PCT / HU98 / 00008 Sec. 371 Date Sep. 25, 1998 Sec. 102(e) Date Sep. 25, 1998 PCT Filed Jan. 26, 1998 PCT Pub. No. WO98 / 33028 PCT Pub. Date Jul. 30, 1998An air-cooled condenser comprising a distributing chamber for distributing a vaporous medium to be condensed, a condensate collecting chamber and finned tubes with fins on air side, said finned tubes being connected in parallel between the distributing chamber and the condensate collecting chamber, where each of the finned tubes comprises two parallel essentially flat side walls and exterior closings connecting the side walls, in the finned tubes there are longitudinal separation walls connected to the side walls and dividing the inner space of the finned tubes into longitudinal parallel channels, and in the separation walls there are breakthroughs and closure elements for allowing the flow of the medium between neighboring channels.

Description

The invention relates to an air-cooled condenser for condensing a vaporous medium, preferably steam.Condensers are widely used in the manufacturing, chemical and energy industry. The air-cooled condenser is a special type of condenser, which generally operates under a vacuum. First of all we shall describe the physical processes that take place in air-cooled condensers, to make sure that the operation of the air-cooled condenser according to the invention is understood.The description of physical processes and of the prior art apply to power plant steam condensers and to condensing steam, but of course the invention is not restricted to this type of condenser: they can also be used as applicable in other places and for other vaporous mediums where air-cooled condensers are required.Air-cooled steam condensers generally consist of a large number of tubes connected in parallel which are densely finned on the air side. The processes taking place in the parallel tubes are principally id...

AI Technical Summary

Benefits of technology

ensures that the freezing of the pipes can be safely avoided;

This embodiment enables that all condenser tubes of the condenser can be of the same type, i.e. it is not necessary to design and manufacture a separate condenser and after-cooler, as well as a connecting tube. Thanks to this embodiment air plugs do not develop as a result of a change in the temperature of the cooling air or as a result of the lack of balance in steam distribution. The after-cooler is in metallic contact with the main condenser, from which in this way sufficient heat is transferred to the high air content sections around the air extraction pipe all the time, so that the sections may not freeze up.

The closure elements and the breakthroughs adjacent to them are arranged in the channels preferably in such a way that they prevent formation of air plugs within the channels. Starting from the exterior channel preferably about half of the channels are provided with said closure elements. In this way a continuously narrowing cross-section for the medium is ensured.

In another preferred embodiment of the condenser each separation wall includes a number of breakthroughs, said breakthroughs are preferably formed equally spaced in the separation wall. Also in this way the developing of air plugs within the channels having a stronger cooling can be prevented as it is possible for the medium to flow through the breakthroughs in that channels where due to the faster condensation of the medium the pressure of the condensation space drops.

Problems solved by technology

The arrangement according to FIG. 1 also entails the disadvantages that due to the under-cooling of the steam space the temperature of the condensate 5 is lower than the theoretical condensation temperature, and when this condensate 5 is returned to the steam turbine cycle, it deteriorates the thermal efficiency of the system.

A further undesirable effect is that due to the higher partial pressure of air and as a result of the under-cooling of the condensate 5, the latter absorbs a higher than permissible volume of oxygen, which could cause corrosion and require degassing prior to returning to the cycle.

It is shown that the correct arrangement and dimensioning of the after-cooler 15 is an extremely difficult task.

The increasing air concentration dramatically increases the under-cooling of the steam space, and deteriorates the heat transfer coefficient, which entails a reduction in the heat dissipation of the condenser and may also cause a frost risk in cold weather.

Since at the air extraction pipe 8 only extremely low volumes are flowing, fresh steam coming to this point even in a small volume could lead to the detrimental effects above.

In the stagnating zone filled up with air, the heat dissipation decreases and in a cold weather, frost risk may prevail.

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